Preparation of norbornene monomers is well known. Dicyclopentadiene can be made by dimerizing cyclopentadiene by a Diels-Alder reaction whereas dihydrodicyclopentadiene can be made by the Diels-Alder reaction of cyclopentadiene and cyclopentene. Norbornenes can also be prepared by the Diels-Alder reaction of cyclopentadiene with selected olefins to yield either norbornene or substituted norbornenes. Tetracyclododecene compounds are byproducts formed from the Diels-Alder reaction of cyclopentadiene and norbornenes. Symmetrical and unsymmetrical trimers and tetramers of cyclopentadiene can, likewise, be prepared by the Diels-Alder reaction of cyclopentadiene.
Norbornene polymeric materials, i.e., those prepared from monomers containing a norbornene moiety, are well known. They can be prepared as elastomers, which are flexible at room temperature, or as plastics, which are rigid at room temperature. Although essentially all of the important physical properties of the norbornene polymeric materials are outstanding, their resistance to oxidation is less than desired. It is, therefore, an object of this invention to stabilize norbornene polymeric materials against oxidative degradation.